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On the grounds of Tripler Army Medical Center, water pouring out of a snaking garden hose keeps a natural stream from drying up. It also keeps alive the breeding grounds of a fragile winged insect found almost nowhere else on earth.

The slow-moving stream, helped along by human intervention, is the last remaining home of Oahu’s only population of the orangeblack Hawaiian damselfly. Before researchers from the Bishop Museum discovered damselflies in this unlikely habitat in 1994, the endangered, slender-bodied cousin of the dragonfly had not been seen on Oahu since the late 1970s. 

how many of Hawaii’s 8,000 or so native insect species, two-thirds of them found nowhere else, are extinct. Many of them have not been studied. It’s difficult for biologists to ascertain exactly what has been lost irrevocably and what is threatened, or on the verge of extinction, but can still be saved. 

The orangeblack Hawaiian damselfly falls under the latter category. One of about 25 damselfly species endemic to Hawaii, the insect has been studied well enough that scientists were able to prove in 2016 that it on the federal endangered species list. The designation unlocked giant opportunities for conservation funding. 

And so a multi-agency partnership of scientists soon hatched a plan: Rear damselflies in captivity with the goal of returning them to nature, where, with luck and a careful strategy, they might form the island’s second damselfly population. If successful, scientists hope to repeat this process over and over again until the native insect establishes a reinvigorated presence on Hawaii’s most populous isle.

Leading this charge is Will Haines, a self-described “bug guy” and a research entomologist who started captive rearing of orangeblack Hawaiian damselflies in a lab last November. He’s employed by the University of Hawaii, but his work with damselflies is funded through the state Department of Land and Natural Resources.

Haines grew up catching native damselflies in his backyard near the Maliko Gulch on Maui. Even now in adulthood, a boyish fascination with creepy crawlers is something Haines said he never really shook off. 

Known as the endangered species capital of the world, Hawaii is home to hundreds of types of threatened plants and animals. Many varieties of flora and fauna found only in Hawaii are down to just a handful of specimens or fewer. 

Insects are of particular import, Haines said, because they account for the vast majority of Hawaii’s biodiversity. The loss of even one of these intricate species could undermine the natural world’s resiliency, disrupt the food web and hamper humankind’s ability to adapt to a dramatically changing climate. 

Haines said he is attracted to working with the orangeblack Hawaiian damselfly because it still has a fighting chance at survival. But bringing it back from the brink won’t be easy. Scientists have been trying to foster a new damselfly population at different sites on Oahu for more than two decades. None of these efforts have been successful.

When a reporter asks Haines to articulate why this particular insect, or any insect species, is worth saving, he offers two reasons — one sentimental and the other pragmatic. 

“Each species is analogous to a work of art, in a way,” Haines said. “It’s a product of millions of years of evolution, and extinction would wipe that out forever. It’s unrecoverable. 

“So my take is, just like we would work to protect the Mona Lisa, which is the product of human ingenuity, we should, if we can, do the same for these unique products of evolution that can not be recovered once they’re gone.”

If that’s not convincing enough for you, Haines offers this rationalization: “Write that they eat mosquitoes.”

Demise Of The Damselfly

Orangeblack Hawaiian damselflies were once commonplace in backyard ponds, lowland taro patches and estuaries. That changed in 1905, when biologists introduced non-native mosquitofish into the Hawaiian watershed as a mechanism to suppress irritating, disease-carrying mosquitoes. 

The fish swiftly grew pervasive in damselfly habitat, preying on mosquitoes but also on damselflies and other aquatic native insects. Damselfly populations were ultimately decimated as an unintended consequence of the biocontrol experiment.

A young naiad in the lab eats brine shrimp larvae served by a lab technician. A newly hatched naiad is the size of a flake of salt and can consume meals larger than itself.

The damselfly still survives in brackish coastal pools in east Maui and in the lower reaches of a few freshwater streams in west Maui. On the Big Island, the species persists in brackish, fish-free pools along the Kona coast. And then there’s the shallow, garden hose-fed stream at Tripler.

“It’s incredible that they’re still here, decades after we thought there weren’t any left on Oahu,” Haines said. 

His job is to collect damselfly eggs on leafy vines along the Tripler stream, hatch them in a lab and rear them over the course of the immature naiad stage. This is the phase of life when a damselfly is a tiny aquatic swimmer. With strict temperature controls and meals of crustaceans and brine shrimp larvae, he supervises their growth from a microscopic egg into a “wriggling piece of dust” over a period of about two months. 

Haines’ work rearing damselflies isn’t about the individual insects. It’s about the perpetuation of the species as a whole, the survival of the crop.

Yet although they are nameless and lacking in personality traits, Haines said he still has an affection for the bugs he’s raising.

“They’re super cute,” he said. “The larvae are like little eating machines. Our employees, when they’re feeding them, sometimes you’ll hear one of them squeal — not the damselflies, the employees — because when they catch their prey it’s just kind of exciting.”

An Experiment Gone Awry

Naiads stop eating about two months after they hatch, when they’re about a centimeter long. That’s Haines’ cue to transport the naiads to their new home in nature. They’ll molt a few days later, crawling out of their skin as a mature winged adult. 

Lyon Arboretum is one of the translocation sites where Haines and his interagency partners have tried to launch a new damselfly population. Earlier this year he helped release naiads there in ponds where non-native fish had been removed. 

The naiads hatched into adults, found mates and laid eggs — but that’s where the experiment went awry. Instead of laying their eggs in the predator-free ponds prepared for them, the damselflies laid them in a nearby taro patch teeming with mosquitofish. None of the naiads born of that experiment survived. 

Female damselflies can lay hundreds of eggs in under 20 minutes, but few of the naiads that hatch survive. Naiads are cannibalistic and eat one another. They are also easy prey for mosquitofish, crayfish and frogs.

Haines called it a “successful failure.” It taught him that the process works — he just need to release the naiads into a predator-free water feature that’s not in close proximity to another, treacherous water source.

The other site Haines and his colleagues have tried out is a shallow, slow-moving stream at Waianae Kai Forest Reserve. Haines’ first attempts there in January and February were thwarted by unusually cold temperatures.

The stream dropped below 55 degrees shortly after the naiads were unleashed into it. And this, Haines said, could have slowed down their development, in turn making them more vulnerable to predators, such as the Japanese wrinkled frogs that hunt for food along the streambed. 

Another possibility: The cold weather was accompanied by heavy rains, which could have washed the naiads out of the stream altogether.

Now Haines and his team are ready to take what they learned from these failed experiments and try again at the same Waianae stream. Armed with sharper knowledge about damselfly egg-laying behavior and gifted with favorable summer weather, Haines said he thinks he’s got a pretty good shot at fostering a successful naiad release.

“I feel optimistic,” said Haines, as he rounds a turn off of Farrington Highway into the state forest reserve. “I mean, we’re pretty new to the game and we’re building on the knowledge of everyone who tried doing this before us. The general thought from everybody seems to be that we’re really close to getting it right.”

Dead Skins: A Sign Of Success

Haines hops out of the driver’s seat, unpacks 75 naiads from a cooler strapped in the truck bed, deposits them into his backpack and hikes into the steamy forest reserve. 

When he arrives at the release site, he checks on the tub of water set beside the stream where, a week ago, he released a preliminary batch of 37 naiads. 

Sticks protrude from the water tub, which is covered with a layer of chicken wire. The wire prevents frogs from hopping in and feasting on defenseless naiads.

Affixed to the sticks, Haines finds what he’d been hoping for: the molted skins of two dozen naiads. The grayish dime-sized skins are a welcome sign that the naiads from the first release have developed into winged adults and flown away. It’s an early indicator of success.

“There was something nagging at me a little bit, like what if a frog figures it out and we get there and there’s a fat frog sitting there after taking out all the naiads,” Haines said. “But this is awesome, actually.”

The real litmus test comes with time. A year from now, if a damselfly population persists at the stream site, Haines and his colleagues will claim victory. For now, they schedule weekly releases, monitor the site and wait.

After the naiad stage, an adult damselfly lives for up to two months. The insect’s main job is to find a mate and replace itself. 

A female damselfly can lay hundreds of eggs in under 20 minutes. But few of them survive.

Naiads eat one another, which is why, in the lab, Haines keeps each naiad isolated in its own cup. 

In the lab, the mortality rate among naiads is about 10 percent. In nature, it’s much, much higher, not only due to predators but due to their own cannibalism.

“It’s sort of this strategy where the female lays hundreds of eggs,” Haines explains. “She assumes that most of them are going to get eaten either by other things or by each other, but then the strongest survive.”

Haines hovers over the water tub and, with a pair of tweezers, collects the molted skins left over from the first naiad release. He deposits them into a container. This way he won’t double-count the skins when he returns to the site next week to monitor the results of the second naiad release and start a third one.

Haines unpacks the naiads he carried in on his back. Each naiad is sequestered in a clear container shaped like a film canister. He pops open the top and dips the lip underwater. He waits a moment while the naiad swims out into the tub. 

One by one, 75 naiads wriggle into the artificial pond, a last measure of protection against predators. If all goes well, the naiads will climb the sticks protruding from the tub and molt out of their skins before Haines returns to the site next week. 

Then they’ll fly off to find a mate. What happens next is up to nature.